We have a Cisco PIX 501 Firewall running PIX version 6.3 with NDM
version 3.0.

The firewall is connected to an SDSL router which has a fixed external
IP address. We'll refer to that as 333.333.333.442 which we all know
is fake.

Behind the firewall are our switches and our internal network with
fixed IP addresses which we will say are in the 10.10.0.x
(255.255.255.0) range. The fireall itself being 10.10.10.254.

Everything works wonderfully at the moment in that all of our computers
behind the firewall have access to all aspects of the Internet without
any problems. We are using PAT tranlation and it works fine.

We now want to be able to access a web site, which is on one of our
servers, from the other side of the firewall (i.e. the Internet).
Let's say that server is on 10.10.0.99 on the inside of the network.

With the firewalls I have worked with before (mostly NetGear) I would
create a new service and assign it to a port (from 90 to 90 for
example). I would then create a rule which would assign that service
to an IP address on the inside of the network (in this case
10.10.0.99). I would then be able to connect to that site by
http://333.333.333.442:90

I assume that is the general concept of what I need to do on this
firewall but I have not been able to figure out how to do so.

I am hoping this is relatively straightforward as I'm sure I'm not the
first who has ever had this basic sort of need.

Can anyone help me with setting this up?

Thank you in advance for any assistance, suggestions or "direction
pointing" you may provide.